[sane-devel] Invalid argument (status 4) when calling sane_start

[Gerard Klaver]

On Sat, 2007-12-15 at 07:59 -0500, m. allan noah wrote:
> The sane v4l support is probably broken, as that code is unmaintained.
> you could enable debugging info for it, but then you would have to
> start fixing the backend. better to get a supported scanner.
> 
> allan
> 
> On 12/15/07, Peter Gebauer <petgeb at users.sourceforge.net> wrote:
> > Hello!
> >
> > When I call sane_start() it returns SANE_STATUS_INVAL (4). This happens both
> > when I use the API and the scanimage binary.
> >
> > scanimage -L reveals:
> > device `v4l:/dev/video0' is a Noname Logitech QuickCam Pro 4000 virtual device
> >
> > I don't have anything else to test with, but I pressume grabbing an image
> > from a v4l device works since SANE does find it as a device to begin with.
> > Or is there some flag I can check to see whether or not this device is
> > actualy supported by SANE?
> >
> > This is what the documentation says
> >  "The scan cannot be started with the current set of options. The frontend
> > should reload the option descriptors, as if SANE_INFO_RELOAD_OPTIONS had
> > been returned from a call to sane_control_option(), since the device's
> > capabilities may have changed."
> >
> > I have made no changes to the options and the option descriptor was loaded
> > just moments before. Also, the options are totally irrelevant to me, just
> > grab the image already! How can I solve this problem?
> >
> > /Peter
> >

Seems your webcam is supported by the pwc kernel module see
http://www.quickcamteam.net/hcl/linux/logitech-webcams

so it should work with most v4l frontends.

Voor using the v4l backend you can try xcam, the v4l backend will use the pwc kernel module to get images.

The v4l backend supports only a few modes so you have to select the correct ones to get a image.
-- 
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m.vr.gr.
Gerard Klaver